The Resource Reservation Setup Protocol (RSVP) is a communications protocol that enables the reservation of resources for packet flows from a source device to a destination device. Using RSVP, a source device can request a Quality-of-Service (QoS) class that supports a level of communication throughput, typically including a defined bandwidth allocation and burst size. RSVP-enabled routers forward the request, and establish a defined route within the network able to commit the resources to satisfy the request. Devices often employ resource reservation techniques to support transmission of real-time data, such as video of voice data, over packet-based networks.
Although advantageous in that it allows the specification of QoS classes and the reservation of end-to-end resources, the support of the RSVP protocol or other resource reservation protocols can introduce significant overhead within a network. Routing devices handling the packet flow along the reserved route, for example, must continually monitor resource allocation and maintain significant state data related to the route. As a result, support for such protocols can be difficult in networks, especially large networks, such as the Internet, in which there may tens of thousands of devices concurrently reserving and making use of resources along end-to-end routes.